1. Field of the Invention
This invention relates to an acoustical barrier for reducing the transfer of sound through a panel member; and more specifically, to a wall-mounted acoustical barrier with a decoupler for separating the acoustical barrier from the panel to enhance the sound reducing properties of the acoustical barrier.
2. Description of Related Art
Acoustical barriers are commonly used in contemporary motor vehicles to reduce engine and road noise. Most vehicles have a sheet metal barrier wall, a firewall, between the engine compartment and the passenger compartment, physically separating the engine compartment and the passenger compartment. Unfortunately, the metal barrier wall readily transmits sound from the engine compartment into the passenger compartment.
Previous acoustical barriers have been constructed to reduce or eliminate sound transfer through the barrier wall. Typically, these prior acoustic barriers generally comprises a slab or cast foam or other decoupling layer and a mass layer, both of which are sheets coextensive with the barrier wall. The foam layer is positioned against the barrier wall and the mass layer overlies the foam layer within the passenger compartment. The foam layer serves to separate or decouple the mass layer from the barrier wall to minimize the transmission of sound vibrations through the mass layer.
In order to maximize sound decoupling, the mass layer should be spaced a predetermined distance from the barrier wall, which is typically established by the thickness of the decoupling layer. The decoupling layer has a predetermined minimal thickness so as to provide sufficient sound attenuation between the barrier wall and the mass layer. Acoustic barriers commonly use a slab or cast foam as the decoupling layer. The slab is typically of uniform thickness before installation, and portions of the decoupling layer corresponding to unrecessed areas of the barrier wall are compressed so that the one side of the decoupling layer conforms to the surface of the barrier wall, while the other side conforms to the surface of the mass layer. Cast foam is variable in thickness and typically fills the entire space between the barrier wall and the mass layer with foam. Although the previous solutions are acceptable, excess decoupling material must be used. The present invention relates to an acoustical barrier that minimizes the amount of decoupling material and production costs in the decoupler.